Effect of blending sequence on the microstructure and properties of PBT/EVA-g-MAH/organoclay ternary nanocomposites

Ternary nanocomposites based on poly(butylene terephthalate) (PBT), maleic anhydride grafted poly(ethylene-co-vinyl acetate) (EVA-g-MAH), and organically modified montmorillonite (organoclays) were prepared through four different blending sequences in a Haake rheocord mixer: (1) To blend PBT, EVA-g-MAH and organoclays in one step; (2) First to prepare EVA-g-MAH/organoclay nanocomposite, then mix it with PBT to get the final nanocomposite; (3) To mix PBT with organoclays first, then the PBT/organoclay nanocomposite with EVA-g-MAH. (4) To mix organoclays with the PBT/EVA-g-MAH blend. The microstructure of the PBT/EVA-g-MAH/organoclay ternary hybrids was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the blending sequence significantly influences the microstructure of PBT/EVA-g-NLAH/organoclay ternary hybrids and the dispersion behavior of the organoclays in the polymer matrix. Tensile and impact properties of the hybrids were also studied. The results showed that the mixing sequence (2) gives the best tensile and impact strength due to its fine "sea-island" morphology of PBT/EVA-g-MAH blend and good dispersion of the organoclays in the continuous PBT matrix.